Generalized-gradient-approximation study of the magnetic and cohesive properties of bcc, fcc, and hcp Mn

Magnetic and cohesive properties of bcc, fcc, and ideal hcp Mn are calculated by use of the generalized gradient approximation proposed by Perdew and Wang [Phys. Rev. B 33, 8800 (1986)] and Perdew [Phys. Rev. B 33, 8822 (1986)]. Calculated results predict correctly an antiferromagnetic ground state for the fcc structure with lattice constant and magnetic moment in good agreement with experimental values. An investigation of the contribution to the free energy from lattice vibration by use of the quasiharmonic approximation removes apparent difficulties involving an hcp ground state in the calculated total energies of three structures.